In the field of ophthalmology, the regeneration of a healthy ocular surface epithelium after traumatic injury or reconstruction techniques is one of the most difficult challenges for repair, and sometimes arise structural changes (vascularization and scarring, epithelial erosions or ulcerations occur among others) and/or functional (corneal opacity or lack of transparency) of undesirable consequences (Maldonado, 1995).
Regardless of origin, tissue damage is accompanied by complex systems of reparation for a high level of organization and differentiation, whose mechanisms are activated immediately after the aggression for proper restoration of the structures (Huang, 1991).
The healing consists of multiple processes, including migration of adjacent cells, mitosis (Kuwara, 1976), cell proliferation and differentiation and rearrangement structures of adhesion of extracellular matrix (Kaufman, 2009).
When the healing process fails to regenerate normal tissue transparency, is produced an opaque scar tissue, and depending on the severity of the case, can lead to visual defects (Rojas, 2009).
With the intraocular application of certain products, it is intended that the healing is complete with stable epithelium, minimal scarring, and prevent conjunctivalization and neovascularization (EMA, 2013).
Corneal epithelium integrity plays a pivotal role in maintaining health ocular surface (Tseng et al., 1997). Clinical conditions associated with epithelial defects and persistent and progressive corneal ulcers include “viral infections, autoimmune and endocrine diseases, thermal and chemical burns, and multiple ocular surgeries”, according to Emiliano Ghinelli in US patent 20080108045.
Healing of the corneal epithelium is compromised by several ocular surgical procedures and is associated with numerous disease states. Delays in the reconstitution of the corneal epithelium, may result in permanent structural and functional perturbations with undesirable consequences (Maldonado, 1995).
According to Claes H. Dohlman “The corneal epithelium fulfills important functions since its absence or disease can lead to serious consequences. In the presence of a long-standing epithelial defect, the stromal surface dries easily and becomes irregular, the stroma swell, and clouds, ulceration and scarring may follow, and the entire eye becomes vulnerable to infection.
In the healed stage, the epithelium may have developed surface irregularities and reduced transparency. Such residual damage of the epithelium, resulting from acute or chronic disease or injury, is responsible for reduction of vision in an enormous number of people the world over.” (Dohlman, 1971).
Good vision contributes greatly to a person's ability to interact with and function in his or her environment. Diseases of and injuries to the eyes can be severely debilitating and occur in a wide variety of forms.
In the treatment of various pathologies of the ocular surface have been used with varying success, the following:
Amniotic membrane transplantation (Koizumi 2000) Autologous transplantation of nasal mucosa (Kuckelkom 1994), oral mucosa (Shore 1992), Tenon orbital (Teping 1989), artificial epithelium (Reim 1990) conjunctival transplantation (Thoft 1979) and treatment with autologous serum among others (Geerling 2004; Kojina 2005).
Particularly the amniotic membrane has been used to solve various problems of the ocular surface in at least 20 ophthalmic procedures, including persistent corneal epithelial defects, pterygium surgery, and conjunctival defects after removal of superficial tumors, acute and chronic chemical injuries, Steven Johnson syndrome, and in the treatment of ocular cicatricial pemphigoid among others (Sangwan 2007).
The amniotic membrane and chorion has been used in surgeries, documented as early as 1910 with the use by Davis on burned and ulcerated skin (Davis 1910)
The isolated amnion alone was first used by Brindeau in 1935 and Burger in 1937 as a graft in forming artificial vaginas. Between 1941 and 1948, Kubanyi used “live” amnion in patients with burns, traumatic skin wounds, and enterocutaneous fistula secondary to surgery for lysis of adhesions. The isolated amnion, with preservation in a technique termed “amnioplastin”, was first reported by Chao and associates in 1940. Chao used amnioplastin for continual dural repair, peripheral nerve injuries, conjunctival graft and flexor and tendon repair. In the Russian literature, this technique was also used for fresh trauma by Pikin in 1942.
In ophthalmology, the use of an amniotic membrane was first reported by De Rotth in 1940 for treatment of conjunctival tissue loss (De Rotth A., Arch. Ophthalmol., 23:525-5 (1940)). In 1993, Batle and Perdomo reintroduced the use of an amniotic membrane as a conjunctival substitute (Batle J F, Perdomo F J, Ophthalmol., 100:107 (1993).
Kim and Tseng then showed in 1995 that an amniotic membrane facilitated corneal surface reconstruction in rabbits after epithelial removal and limbal lamella keratectomy and introduce a method of preservation and storage of this material (Kim J C and Tseng S C, Cornea, 14:473-84 (1995)).
Presently, the amniotic membrane has been recognized as an excellent material for the treatment of certain ocular disorders such as persistent corneal epithelial defects with ulceration, pterygium and for conjunctival surface reconstruction (Baradaran 2007).
It is noteworthy that the amniotic membrane has a thick basement membrane, which in the likeness of ocular tissues, and indicate that this material can replace conjunctival basement membrane and promote epithelialization (Fukuda 1999).
International patent application number PCTVUS2003/029390 from Ghinelli describes the use of a human amniotic membrane for prophylaxis and treatment of diseases and conditions of the eye and skin.
Several methods for the preparation of amniotic membranes for surgery have been described. These include alcohol dehydration, preservation in antibiotics in saline, either with or without separation of the amniotic and chorionic layers (Dua 1999).
Other methods have been disclosed more recently. For example, Tseng (U.S. Pat. Nos. 6,152,142 and 6,326,019B1) discloses a method relying on freezing for preservation of the amniotic membrane; Hariri et al, (US Patent 20040048796) disclose a method designed to decellularise the amniotic membrane leaving it devoid of all but a collagenous membrane.
The use of amniotic membrane as a technique of choice in certain pathologies of the ocular surface with conjunctival involvement (pterygium, especially primary, symblepharon and sinequiantes processes with restricted ocular motility), found a higher recurrence of pathology prior and more aggressively after transplantation of said material (Lopez, 2012).
Unfortunately, an improvement in the patient's visual outcome following application of amniotic membrane tissue is often unsuccessful (Solomon et al., 2002). U.S. Pat. No. 7,494,802 by Scheffer observed an early dissolution of the AmnioGraft™, i.e., shorter than one week in human patients with an exposure problem.
And Dua, in his patents US20080193554, and WO2007010305A3 detected inconsistencies in the clinical outcome following the use of amniotic membrane and refer: “in the treatment of certain conditions have been observed within the inventors' clinical practice, including excessive scarring in severe conjunctival wounds”.
In preparing competitive products, after the human extraction of the raw material, sophisticated laboratory equipment and manufacturing expertise is needed (for example, Engineers and personnel for the assembly and processing) before obtaining the final product.
The main limitation of these products is their expense: high price in order to compensate the high investment cost.
There is an ongoing need for alternative therapies for the treatment of ocular diseases and injuries, particularly low-cost therapies that are readily accessible and easy to use.
It should be noted that in the process for the purification and isolation of the tunica serosa from the small intestine of porcine tissue (or serous membrane), which comply with all rules and regulations, the sophisticated processes of competitor are simplified, with lower costs and less human skill to prepare the final product.
The serous membrane of the present invention is abundant, inexpensive and the methods to process provide effortlessness to manufacture while the competitors require high degrees of synthesis which drive up costs.
Constituents of the Fine Structure of the Intestinal Serosa
The microscopic observation shows that a three-layered serous membrane (the Latin anatomical name is tunica serosa) is structurally composed of one layer of squamous epithelial cells (simple squamous epithelium), known as mesothelium, which face the peritoneal cavity, which rests on a basement membrane (basal lamina) and a deeper layer of loose connective tissue (Janik, 1982; Whitaker, 1982; Eroschenko, 2008; Van der Flier, 2009).
For purposes of the patent, it is necessary to do a more extensive description of two of these structures: the mesothelium and the basement membrane, and past use of the Golbeater's Skin.
The Mesothelium
The epithelial layer, known as mesothelium (that covers the external surfaces of the digestive organs, lungs, and heart), consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. These cells are bound tightly to the underlying connective tissue (Eroschenko, 2008).
The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities and internal organs (Eroschenko, 2008).
Morphological studies of the mesothelium of several mammalian species, including rat, mouse, dog, hamster, rabbit, horse and humans have shown, with minor exceptions, which are essentially similar irrespective of species or anatomical site. (Whitaker, 1982; Odor, 1954).
The main purpose of these cells is to produce a lubricating fluid that is released between layers, providing a slippery, non-adhesive, and protective surface (Van der Flier, 2009).
With the gradual accumulation of information over the years, the mesothelium is now recognized as a dynamic cellular membrane with many important functions (Mutsaers, 2002).
These include transport and movement of fluid and particulate matter across the serosal cavities, leucocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix proteins to aid in serosal repair, release of factors to promote both the deposition and clearance of fibrin, antigen presentation, immune surveillance, and regulation of inflammatory processes and wound healing (Mutsaers, 2002).
The Basement Membrane
The basement membrane is a specialized extracellular matrix compartment, which participates dynamic and active in important roles in cell differentiation, tissue architecture and repair mechanisms (Martinez, 1983; Weber, 1964).
It is recognized that the intact basement membrane is vital to the control of normal growth and epithelial differentiation (Stoker, 1990) and pre-existing components are required to promote the reconstruction of the basement membrane (Andriani, 2003; Herrick, 2007).
Typical, “common” basement membranes are usually described as being composed of three layers (Kefalides et al., 1979).
The dense sheet, the lamina lucida, and fibroreticular sheet, which basement membrane attached to the underlying connective tissue (Kefalides, 1979; Vracko, 1974; Madri, 1984, Inoue, 1983).
The lamina densa, the main layer of the basement membrane, is separated from the surface of adjacent cells by a lucent layer or space, the lamina lucida, while the third layer, the lamina (or pars) fibrorecticularis, forms a transitional zone between the lamina densa and connective tissue (Mutsaers, 2002; Dohlman, 1971).
Basement membranes are extracellular sheet-like layers, no wider than 200 nm, which separate certain tissues including epithelia, endothelia, muscle fibers, and the nervous system, from connective tissue compartments (Kefalides et al., 1979; Inoue, 1989).
Basement membrane of the corneal epithelium is not in any way unique—most epithelia of the body have a similar structure—but it may be of critical importance to the adhesion of the corneal epithelium in a way not quite understood (Goldman, 1969).
If the basement membrane is surgically removed, the development of epithelial adhesion is much slower (Goldman, 1969). Long-standing epithelial defects and recurrent erosion in the eyes of patients may be explained by damage to the basement membrane (Goldman, 1969).
Eventually, however, the epithelium secretes new basement membrane and becomes well attached again to the rest of the cornea (Dohlman, 1971). Basement membrane that provides support to the corneal epithelium is important in maintaining cell polarity and in wound healing processes (Maldonado, 1995).
Taking advantage of its basement membrane content, in a similar way to the amniotic membrane, the new serous membrane (or serosa) has in its constitution a basal membrane, as preexisting component can accelerate the reconstruction of the ocular structure.
Golbeater's Skin
Golbeater's Skin or intestinal serous membrane has a long history. The Ebers Papyrus compiled around 3750 B.C. describes Egyptian surgeons using dried intestine for suturing wounds. And the gold leaf that adorns ancient sarcophagi was made with “goldbeater's skin,” the incredibly thin but strong outer membrane of calf intestine (Schwarcz, 2013).
Egyptian craftsmen managed to produce gold leaf that was an almost unimaginable 0.000125 millimetres thick and separating the layers with “goldbeater's skin” was critical to prevent the leaves from fusing together (Schwarcz, 2013).
Antoine Germain Labarraque, solved the problem of stench in the “boyauderies,” the factories where animal guts were turned into strings for musical instruments, sutures and “goldbeater's skin” (Schwarcz, 2013).
Joseph Thomas Clover in 1862 invented an apparatus for the inhalation of chloroform “Clover portable regulating ether inhaler”. This consisted of a large reservoir bag lined with goldbeater's skin. (Sykes, 1960).
U.S. Pat. No. 174,465 was issued to Alexander Graham Bell in 1876, which used to build your stretched diaphragm or drum with goldbeater's skin.
It has also been reported using when repairing holes and tears of damaged parchment manuscripts. “ . . . on Sep. 30, 1898, at the second meeting of the Society Bibliographica Italiana in Turin, report from Franz Ehrle, s.j., . . . spoke . . . about the severe degradation of paper . . . and the need to find ways to staunch the massive destruction that threatens millions of items and the discussion turned to the use of Goldbeater's skin” (Ehrle, 1909).
U.S. Pat. No. 552,612 in Jan. 7, 1896 was issued to Warren Herbert Frost for the construction of their musical instrument “Zobo” by diaphragm made from goldbeater's skin.
Around 1912 the Germans adopted the material for the internal gas bags of the “Zeppelin” and then used in the USS Shenandoah. (Steadman, 2006).
To date, other industrial application of these sheets can be used to make clarinet, piccolo, or flute pads or in the Talas Online catalogue used for repairing parchment and vellum.
U.S. Pat. No. 3,562,920 entitled “Tubular sheet and strip form prostheses on a basis of biological tissue” in Feb. 16, 1971 Berhard Braun use the Goldbeater' skin in his construct.
The 920 Braun Patent comprising a plurality of structural elements to form prosthesis that work together, viewed from the perspective to accomplish the intended use, and must be considered that the individual components not perform the same function derived is needed structural combination to achieve that goal.
Braun uses his discovery to produce prostheses capable “for use as vascular, esophagus, bronchus, intestinal, ureter and cardiac valve prostheses and as other corrective part of various organs such as liver”, “as used for prosthetic repair of the cystic duct, the ureter, the esophagus or, in special cases, blood vessels”. “to close defect in the tympanic membrane and the heart wall, for hollow-walled organs or as heart valves . . . are also used to repair damage to parenchymatous soft tissue, for example, in the liver, kidney, spleen and pancreas.” which is achieved by means of invasive techniques (make cuts in the skin which cause damage to tissue, nerves, and blood vessels) and fixation with sutures, whose use is totally different from the intended use of the graft of the present application.
The U.S. patents: A. U.S. Pat. No. 3,562,920; B. U.S. Pat. No. 5,755,791; and C. PGPUB 2005/0202058 show several common elements: change natural resources (raw materials) for the construction of a finished product with variable layers in sequence, so that the final product is treated as a single unit for interoperability.
When changes are made any change affects the entire model and affecting their attributes. The preparation of the products in this “complex” technology “requires the existence of a rigid structure (hard materials) to ensure the stability of the final product to carry out the proposed function.
In U.S. patent 2005/0202058 by the inventor Michael C. Hiles, the text is not clear, and careful analysis shows that the submucosa plane (site from which 058 patent obtain the extracellular matrix materials) can never include the serous layer in its constitution, because the submucosal plane in the anatomy and histology of the digestive organs lies one level below the serous layer with different structure, cellular composition and bioactive components.
It should be noted a considerable difference between the manner of use of the prosthesis or graft in Patents 920, 791 and 058 and the use the graft of the applicant.
The patents 920, 791 and 058, refer than the graft being placed over vital structures such as vessels (vascular patches), viscera's (esophagus, bronchus, intestinal), or even heart or lung, and also used to repair damage to parenchymatous soft tissue, for example, in the liver, kidney, spleen and pancreas.
To apply the prosthesis or graft of Patents 920, 791 and 058, invasive procedures are required that make cuts in the skin. Tissues, nerves and blood vessels are damaged during these procedures.
By contrast, the procedure of the applicant is a non-invasive technique that does not damage the tissues, and not penetrate the eyes at the site of implantation, that pursues restoring this vital structure. The intended use of the graft in this invention is directed for tissue regeneration and repair damaged ocular surfaces at the site of implantation.
Golbeater's Skin has a long history of use according to the description was described in previous lines and includes use of the product of bovine origin sold in Talas Online catalogue.
Prior experience with this product by the author, to compare materials from the intestines of cattle and pigs the applicant describes the complications associated with the use of this product of bovine origin to be implanted in the wound site, which include rigidity, and higher disadvantage by the damage to the fragile, newly formed epithelium, thus extending healing times, prolong the duration of hospital stays and demand additional therapeutic interventions.
In the Design Control Guidance for Medical Device Manufacturers the U.S. Food and Drug Administration establishes the following Requirements*: “§ 820.3 (s) Quality means the totality of features and characteristics that bear on the ability of a device to satisfy fitness-for-use, including safety and performance (Design Control Guidance for Medical Device Manufacturers 1997)
§ 820.30(f) Design verification. Each manufacturer shall establish and maintain procedures for verifying the device design. Design verification shall confirm that the design output meets the design input requirements. The results of the design verification, including identification of the design, method(s), the date, and the individual(s) performing the verification, shall be documented in the Design History File.
§ 820.3(y) Specification means any requirement with which a product, process, service, or other activity must conform.
§ 820.3(z) Validation means confirmation by examination and provision of objective evidence that the requirements for a specific intended use can be consistently fulfilled. Verification means confirmation by examination and provision of objective evidence that specified requirements have been fulfilled.”* *(http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/PostmarketRequirements/QualitySystemsRegulations/§ 820.3(aa)
The objective of design controls is to ensure adequate oversight by making verification activities explicit and measuring the thoroughness of their execution.
Following are a few examples of verification methods and activities recommended in Design Control Guidance for Medical Device Manufacturers from the US Food and Drug Administration: 1. Failure modes and effects analysis. 2. Package integrity tests. 3. Biocompatibility testing of materials. 4. Bioburden testing of products to be sterilized, which are not followed in any of the preparation processes of the product of bovine origin sold in Talas Online catalogue.
As with any new product, the introduction into clinical use need adequate controlled study, issues involving side effects and the efficacy in the clinical experience.
This can lead to unanswered questions regarding appropriate use and indications of the Golbeater's Skin material from Tales online catalogue.
The applicant aware that the above information may be used to conduct a risk-based assessment before any decision is taken about the use in Goldbeater's skin product for ocular surface lesions and it is not considered that the product meets neither requirement.
Overall, the medical need to replacing the deficient stromal connective tissue as well as stimulating re-epithelialization in the injured ocular surface, has not been met.
As described above, according to the present invention, with the use of serous membrane of the present invention set forth in the examples, it is possible to improve the deficient stromal connective tissue as well as stimulating re-epithelialization in the injured ocular surface, and higher therapeutic effects can be expected.
From a social perspective the product is accessible, reasonably, for the benefit of the population who are economically disadvantaged and, in the future, may need it.
For developing countries, take into account concerns of “access” to technology. The present invention addresses this need.
In summary: technology improves the lives of hundreds of thousands of patients and solves a major problem for the less developed areas of the world by providing an economic product.